1. Field of the Invention
The present invention relates to a local location manager, a home location manager and a mobile communication system, and in particular to a location management method in a local location manager, a home location manager and a mobile communication system.
2. Description of the Prior Art
As is well known, it is common in mobile communication services to store the location of each mobile node, such as a cellular telephone, in a location manager in order that the mobile node can receive an inquiry (incoming call/packet) wherever it is. Specifically, an area for which a mobile communication service is provided is divided in multiple registration areas, and when a mobile node moves from one registration area to another registration area, a location update request, in which a registration area after movement is identified, is sent from the moving node to the mobile network via a base-station apparatus, consuming wireless resources. In response to the location update request, the registration area of each mobile node, which is stored in the location manager is sequentially updated.
However, when there are a lot of passengers carrying a mobile node in a train, for example, a lot of mobile nodes move at the same time as the train moves, and if the train moves from one registration area across to another registration area (i.e. crossing the area), a location update request is sent to a mobile network from each of these mobile nodes via a base-station apparatus. This causes problems such as pressure on wireless resources and temporary, significant increase in communication traffic in the mobile network.
Techniques for solving these problems are disclosed in Patent Document 1 and Non-patent Document 1, for example. In these documents, a mobile communication system is disclosed in which a master-slave relationship is established between a moving body, such as a train, and a mobile node existing in the space of the moving body so that a mobile router installed in the moving body, which is a master, sends a location update request of the mobile nodes, which are slaves, to the mobile network on behalf of the mobile nodes, consuming wireless resources. In this mobile communication system, a mobile node existing in the space of a moving body registers its location with the above mobile router as a virtual base-station apparatus. When the moving body moves from one registration area to another registration area, the mobile router sends a location update request to the mobile network via a base-station apparatus. In this way, it is realized that the mobile router sends a location update request on behalf of mobile nodes existing in the space of a moving body.
(Patent Document 1)
Published Unexamined Patent Application No. 11-355835 (Non-Patent Document 1)
“A Study on Concatenated Mobility Management” by Yumiba, Sasada, Fujiwara and Yabusaki, IEICE Technical Report; IN2000-177, pp. 7-14; February 2001